pi

To find the area of the circular garden, you need to multiply the square of the radius by pi.

(Chinese) 要算出圆形花园的面积，你需要用半径的平方乘以圆周率。

The Greek letter pi is used in physics and engineering formulas worldwide to represent this constant.

(Chinese) 希腊字母π在世界各地的物理和工程公式中被用来代表这个常数。